I have the same problem with my senior pony. He is about 20. I have had him on SmartDigest Ultra for the past 3 or 4 years which has helped him. I also am doing a monthly SandClear cleanse because he used to be on dirt/sand paddocks before I moved to my new barn a year ago. The SandClear seemed to help a bit, but he still has wet poop every third or fourth time passing manure. His poor legs have the same poop running down them problem. I noticed that fresh spring grass causes him to have more squirting than usual, but that is probably not the issue during the winter. I have chalked it up to that just being how he is. Several vets have looked at him over the years, and no one has been too concerned, especially since he has had this problem for about 8 years now. I did not consider SmartGut, but will look into it. We avoid giving him bran mash because we don’t want to exacerbate the problem. We have another senior gelding at my barn that also has the same issue, and he is on the same SandClear regimen. That horse was also kept in a sand/dirt paddock for some part of his life. Both are wormed regularly.